Thermoplastic polyurethanes with improved melt flow

Abstract

A thermoplastic polyurethane elastomer is disclosed obtained by reacting A) diisocyanates, B) polyhydroxy compounds and/or polyamines, with C) as chain extenders mixtures of C1) benzene substituted with at least two hydroxyalkyl, hydroxyalkoxy, aminoalkyl and/or aminoalkoxy groups and C2) an alkanediol with 4 to 44 C atoms. The reaction is further characterized in that the molar ratio C1 to C2=60 to 40 to 95 to 5 and in that the equivalent ratio of NCO groups to the sum of the NCO-reactive groups is about 0.9 to 1.20.

What is claimed is: 
     
       1. A thermoplastic polyurethane elastomer prepared by reacting in the melt A) at least one diisocyanate, and   B) at least one member selected from the group consisting of polyhydroxy compounds and polyamines having a number average molecular weight of about 500 to 10,000, and   C) a chain extending mixture of C1) benzene substituted with at least two substituents selected from the group consisting of hydroxyalkyl, hydroxyalkoxy, aminoalkyl and aminoalkoxy moieties, excluding m-xylylenediamine and   C2) an alkanediol with 4 to 44 carbon atoms, wherein molar ratio of C1:C2=60:40 to 95:5 and wherein the equivalent ratio of NCO groups to the sum of the NCO-reactive groups is about 0.9 to 1.20, said chain extending mixture excluding a mixture of bis(hydroxyethoxy)benzene and 1,4 butanediol.     
     
     
       2. The thermoplastic polyurethane elastomers of claim 1, wherein said C1) has two identical substituents in the 1 and 4 positions. 
     
     
       3. The thermoplastic elastomer of claim 1 wherein said C1) corresponds to   X-Alk-W-Ph-W-Alk-Y,     wherein   X and Y independently denote OH or NH 2 , and   Alk denotes an alkylene group with 1 to 4 carbon atoms, and   W denotes a single chemical bond or an oxygen atom and   Ph denotes a benzene ring.   
     
     
       4. The thermoplastic polyurethane elastomer of claim 1, wherein C1 is 1,4-bis(2-hydroxyethoxy)benzene. 
     
     
       5. A thermoplastic polyurethane elastomer prepared by reacting in the melt A) at least one diisocyanate, and   B) at least one member selected from the group consisting of polyhydroxy compounds and polyamines having a number average molecular weight of about 500 to 10,000, and   C) a chain extending mixture of C1) a compound corresponding to   X-Alk-W-Ph-W-Alk-Y,         wherein   X denotes OH, Y denotes NH 2 , Alk denotes an alkylene group with 1 to 4 carbon atoms, W denotes a single chemical bond or an oxygen atom and Ph denotes a benzene ring, and C2) an alkanediol with 4 to 44 carbon atoms, wherein molar ratio of C1:C2=60:40 to 95:5 and wherein the equivalent ratio of NCO groups to the sum of the NCO-reactive groups is about 0.9 to 1.20.     
     
     
       6. A thermoplastic polyurethane elastomer prepared by reacting in the melt A) at least one diisocyanate, and   B) at least one member selected from the group consisting of polyhydroxy compounds and polyamines having a number average molecular weight of about 500 to 10,000, and   C) a chain extending mixture of C1) benzene substituted with at least two substituents selected from the group consisting of hydroxyalkyl, hydroxyalkoxy, aminoalkyl and aminoalkoxy moieties, excluding m-xylylenediamine and   C2) an alkanediol with 4 to 44 carbon atoms, wherein molar ratio of C1:C2=60:40 to 95:5 and wherein equivalent ratio of NCO groups to the sum of the NCO-reactive groups is about 0.95 to 1.10 and wherein a mixture of bis(hydroxyethoxy)benzene and 1,4 butanediol is excluded.     
     
     
       7. A thermoplastic polyurethane elastomer prepared by reacting in the melt A) at least one diisocyanate, and   B) at least one member selected from the group consisting of polyhydroxy compounds and polyamines having a number average molecular weight of about 500 to 10,000, and   C) a chain extending mixture of C1) at least one member selected from the group consisting of 1,4-bis(2-hydroxyethoxy)benzene, 1,3-bis(2-hydroxyethoxy)benzene, 1,2-bis(2-hydroxyethoxy)benzene, 1,4-bis(hydroxymethyl)benzene and 1,2 bis(hydroxymethyl)-benzene and   C2) at least one member selected from the group consisting of 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol and 1,12-dodecanediol, wherein molar ratio of C1:C2=60:40 to 95:5 and wherein the equivalent ratio of NCO groups to the sum of the NCO-reactive groups is about 0.9 to 1.20 and wherein a mixture of bis(hydroxyethoxy)benzene and 1,4 butanediol is excluded.       
     
     
       8. A thermoplastic polyurethane elastomer prepared by reacting in the melt A) at least one diisocyanate, and   B) at least one member selected from the group consisting of polyhydroxy compounds and polyamines having a number average molecular weight of about 500 to 10,000, and   C) a chain extending mixture of C1) benzene substituted with at least two substituents selected from the group consisting of hydroxyalkyl, hydroxyalkoxy, aminoalkyl and aminoalkoxy moieties, and   C2) an alkanediol with 4 to 44 carbon atoms, wherein molar ratio of C1:C2=75:25 to 90:10 and wherein the equivalent ratio of NCO groups to the sum of the NCO-reactive groups is about 0.9 to 1.20 and wherein a mixture of bis-(hydroxyethoxy)-benzene and 1,4-butanediol is excluded.